1. Field of the Invention
The present invention relates to a manufacturing method of a semiconductor device that uses a substrate provided with a semiconductor layer with an insulating film interposed therebetween, in particular, an SOI (silicon on insulator) substrate.
2. Description of the Related Art
In recent years, integrated circuits that use an SOI (silicon on insulator) substrate in which a thin single crystal semiconductor layer is provided on an insulating surface, instead of a bulk silicon wafer, have been developed. By utilizing characteristics of a thin single crystal silicon film formed over an insulating film, transistors formed in the integrated circuit can be separated from each other completely. Further, since fully-depleted transistors can be formed, a semiconductor integrated circuit with high added value such as high integration, high speed driving, and low power consumption can be realized.
As one of the methods for manufacturing SOI substrates, a Smart Cut (registered trademark) method is given. By a Smart Cut method, an SOI substrate having a single crystal silicon film over not only a silicon substrate but also an insulating substrate such as a glass substrate can be manufactured (see Patent Document 1, for example). A manufacturing method of an SOI substrate having a single crystal silicon thin film over a glass substrate, in which a Smart Cut method is used, is briefly described below. First, a silicon dioxide film is formed over a surface of a single crystal silicon wafer. Next, by implantation of a hydrogen ion into the single crystal silicon wafer, a hydrogen ion implantation plane is formed at a predetermined depth in the single crystal silicon wafer. Then, the single crystal silicon wafer into which the hydrogen ion is implanted is bonded to a glass substrate with the silicon dioxide film interposed therebetween. After that, heat treatment is performed, whereby the hydrogen ion implantation plane serves as a cleavage plane and a thin film of the single crystal silicon wafer into which the hydrogen ion is implanted is separated. In this manner, a single crystal silicon thin film can be formed over the bonded glass substrate. This Smart Cut method may also be referred to as a hydrogen ion implantation separation method.
In manufacturing an SOI substrate by a Smart Cut method or the like, there is a possibility that a defect would be generated in a peripheral portion of a single crystal silicon layer and a bonded insulating layer over a supporting substrate. Therefore, a technique of removing the peripheral portion of the single crystal silicon layer and the bonded insulating layer is disclosed (e.g., see Patent Document 2).